extern char **environ;
An array of strings called the “environment” is made available by execve(2) when a process begins. By convention these strings have the form name=value. The following variables are recognized by various commands:
- The size of the block units used by several commands, most notably df(1), du(1), and ls(1). May be specified in units of a byte by specifying a number, in units of a kilobyte by specifying a number followed by ‘K’ or ‘k’, in units of a megabyte by specifying a number followed by ‘M’ or ‘m’, or in units of a gigabyte by specifying a number followed by ‘G’ or ‘g’. Sizes less than 512 bytes or greater than a gigabyte are ignored.
- A list of startup commands read by ex(1) and vi(1).
- The user's login directory, set by login(1) from the password file passwd(5).
- The login name of the user.
- The sequence of directories, separated by colons, searched by
system(3), execvp(3), etc. when looking for an executable file.
Initially set to the value of
_PATH_DEFPATHby login(1), traditionally /usr/bin:/bin, but expanded to include /usr/sbin, /sbin, /usr/X11R6/bin, /usr/local/bin, and /usr/local/sbin in OpenBSD.
- The name of the default printer to be used by lpq(1), lpr(1), and lprm(1).
- The current working directory.
- The full pathname of the user's login shell.
- The kind of terminal for which output is to be prepared. This information is used by commands such as mandoc(1) which may exploit special terminal capabilities. See /usr/share/misc/termcap (termcap(5)) for a list of terminal types.
- The string describing the terminal in
TERM, or, if it begins with a ‘
/’, the name of the termcap file. See
TERMPATHbelow, termcap(5), and termcap(3).
- A sequence of pathnames of termcap files, separated by colons or spaces,
which are searched for terminal descriptions in the order listed. Having
TERMPATHis equivalent to a
TERMPATHis ignored if
TERMCAPcontains a full pathname.
- The directory in which to store temporary files. Most applications use either /tmp or /var/tmp. Setting this variable will make them use another directory.
- The time zone to use when displaying dates. The normal format is a
pathname relative to /usr/share/zoneinfo. For
example, the command
env TZ=America/Los_Angeles datedisplays the current time in California. See tzset(3) for more information.
- Deprecated synonym of
LOGNAME(for backwards compatibility).
Further names may be placed in the environment by the
export command and
name=value arguments in
sh(1), or by the
setenv command if you use
csh(1). It is
unwise to change certain sh(1) variables that are frequently exported by
.profile files, such as
IFS, unless you
know what you are doing.
The current environment variables can be printed with env(1) or printenv(1).
csh(1), env(1), ex(1), login(1), printenv(1), sh(1), execve(2), execle(3), getenv(3), system(3), termcap(3), tzset(3), termcap(5)
environ manual page appeared in
Version 7 AT&T UNIX.